Publications

Stereo analysis of images obtained during the 2001 flyby of Comet Borrelly by NASA's Deep Space 1 (DS1) probe allows us to quantify the shape and photometric behavior of the nucleus. The shape is complex, with planar facets corresponding to the dark, mottled regions of the surface whereas the bright, smooth regions are convexly curved. The photometric as well as textural differences between these

The Mw7.9 Denali, Alaska earthquake of 3 November, 2002, caused minor damage to at least 20 houseboats in Seattle, Washington by initiating water waves in Lake Union. These water waves were likely initiated during the large amplitude seismic surface waves from this earthquake. Maps of spectral amplification recorded during the Denali earthquake on the Pacific Northwest Seismic Network (PNSN) stron

Black manganese-iron oxide crusts form on most exposed rock on the ocean floor. Such crusts are well developed on the steep lava slopes of the Hawaiian Ridge and have been sampled during dredging and submersible dives. The crusts also occur on fragments detached from bedrock by mass wasting, on submerged coral reefs, and on poorly lithified sedimentary rocks. The thickness of the crusts was measur

Airborne spectral and light detection and ranging (lidar) sensors have been used to quantify biophysical characteristics of tropical forests. Lidar sensors have provided high-resolution data on forest height, canopy topography, volume, and gap size; and provided estimates on number of strata in a forest, successional status of forests, and above-ground biomass. Spectral sensors have provided data

Although rivers provide important biogeochemical inputs to oceans, there are currently no descriptive or predictive relationships of the spatial scales of these river influences. Our combined satellite, laboratory, field and modeling results show that the coastal dispersal areas of small, mountainous rivers exhibit remarkable self-similar scaling relationships over many orders of magnitude. River

Regional seismic waveforms, continuous and campaign-mode GPS data, and surface slip measurements were used to obtain a kinematic model of the rupture process of the November 3, 2002 Mw 7.9 Denali, Alaska, earthquake. The event initiated as a Mw 7.0 reverse slip event on the north-dipping Susitna Glacier fault with subsequent right-lateral slip distributed over approximately 300 km of the Denali fa

Kulshan caldera (4.5×8 km), at the northeast foot of Mount Baker, is filled with rhyodacite ignimbrite (1.15 Ma) and postcaldera lavas and is only the third Quaternary caldera identified in the Cascade arc. A gravity traverse across the caldera yields a steep-sided, symmetrical, complete Bouguer anomaly of −16 mGal centered over the caldera. Density considerations suggest that the caldera fill, wh

We compare the frictional strengths of 17 sheet structure mineral powders, measured under dry and water-saturated conditions, to identify the factors that cause many of them to be relatively weak. The dry coefficient of friction μ ranges upward from 0.2 for graphite, leveling off at 0.8 for margarite, clintonite, gibbsite, kaolinite, and lizardite. The values of μ (dry) correlate directly with cal

A 66-monument geodetic array spanning the Coast Ranges near San Francisco has been surveyed more than eight times by GIPS between late 1993 and early 2001. The measured horizontal velocities of the monuments are well represented by uniform, right-lateral, simple shear parallel to N29°W. (The local strike of the San Andreas Fault is ∼N34°W.) The observed areal dilatation rate of 6.9 ± 10.0 nstrain

Volcanic hazards in Kona (i.e. the western side of the island of Hawai'i) stem primarily from Mauna Loa and Hualālai volcanoes. The former has erupted 39 times since 1832. Lava flows were emplaced in Kona during seven of these eruptions and last impacted Kona in 1950. Hualālai last erupted in ca. 1800. Society's proximity to potential eruptive sources and the potential for relatively fast-moving l

The northeast Mojave domain, a type locality for bookshelf faulting, is a region of east striking, left-lateral faults in the northeast corner of the Mojave block, a block otherwise dominated by ∼N40°W striking, right-lateral faults. Paleomagnetic evidence suggests that blocks within the domain have rotated clockwise about a vertical axis as much as 60° since 12.8 Ma [Schermer et al., 1996]. In 19

Time-dependent closure of fractures in quartz was measured in situ at 22–530°C temperature and 0.1-150 MPa water pressure. Unlike previous crack healing and rock permeability studies, in this study, fracture aperture is monitored directly and continuously using a windowed pressure vessel, a long-working-distance microscope, and reflected-light interferometry. Thus the fracture volume and geometry